Red cell phosphate metabolism in preterm infants with idiopathic respiratory distress syndrome

Phosphate metabolism was studied in twenty-one preterm infants with idiopathic respiratory distress syndrome during and after oxygen (O2) therapy using a hood. Plasma, red cell inorganic phosphate (Pi) and the red cell concentrations of organic phosphate metabolites ATP and 2,3-diphosphoglycerate were significantly lower in the sick infants when compared to controls of similar age and birthweight, and remained low even 24 h after cessation of therapy. Plasma cortisol levels were elevated at the onset of the disease and decreased to almost control levels by the end of O2 therapy while the values of plasma calcitonin did not show any difference from controls. Plasma creatinine phosphokinase and blood lactic acid levels followed the pattern of the control group with a small increase at the beginning of the study and decreasing thereafter. Several factors may be implicated in the cause of hypophosphatemia in these infants such as inadequate feeding, acidosis and hypercortisolaemia due to stress leading to phosphaturia.